A hybrid surface plasmon waveguide (HSPWG) with a convex rib added on the metal surface is further investigated and analyzed theoretically. The high mode confinement and long propagation distance can be realized simultaneously by optimizing the waveguide geometry. Our designed structures can provide mode area and propagation distance achieving close to λ2/512 and 2200 μm respectively, which are better than the performance of the traditional HSPWG. Our structures are excellent, promising candidates for improving plasmonic devices in the fields of ultrafast modulators and low-threshold nanolaser.